Safety of Nasal Influenza Immunisation in Egg Allergic Children - The SNIFFLE 2 Study

Inclusion Criteria: * Aged 2 - 17 years old * Physician-diagnosis of egg allergy Exclusion Criteria: 1. Clinical resolution of egg allergy 2. Contraindications to LAIV (notwithstanding allergy to egg protein): * Hypersensitivity to the active ingredients, gelatin or gentamicin (a possible trace residue) * Previous systemic allergic reaction to LAIV * Previous allergic reaction to an influenza vaccine (not LAIV) is a relative contra-indication, which must be discussed with the site PI to confirm patient suitability * Children/adolescents who are clinically immunodeficient due to conditions or immunosuppressive therapy such as: acute and chronic leukaemias; lymphoma; symptomatic HIV infection; cellular immune deficiencies; and high-dose corticosteroids. NB: LAIV is not contraindicated for use in individuals with asymptomatic HIV infection; or individuals who are receiving topical/inhaled corticosteroids or low-dose systemic corticosteroids or those receiving corticosteroids as replacement therapy, e.g. for adrenal insufficiency. * Children and adolescents younger than 18 years of age receiving salicylate therapy because of the association of Reye's syndrome with salicylates and wild-type influenza infection. 3. Contraindication to vaccination on that occasion, due to child being acutely unwell: * Febrile ≥38.0oC in last 72 hours * Acute wheeze in last 72 hours requiring treatment beyond that normally prescribed for regular use by the child's treating healthcare professional * Recent admission to hospital in last 2 weeks for acute asthma * Current oral steroid for asthma exacerbation or course completed within last 2 weeks